By James R. Steiger, Erin L. Miller, and Patricia Saccone
This article is a part of the May/June 2018, Volume 30, Number 3, Audiology Today issue.
In 2005, James R. Steiger, PhD, published Audiologic Referral Criteria: Sample Clinic Guidelines. Those guidelines included sample referral guidelines for hearing aid use, for the identification of vestibular schwannomas, and for the identification of middle-ear disorder with wide-width and narrow-width tympanograms. Considering the passage of time since that paper was published, and the absence of a discussion of tinnitus, vestibular disorders, and sudden sensorineural hearing loss in that paper, it seemed prudent to revisit the topic. This is a synopsis of referral options and considerations that may augment clinical judgment, with a basic decision-making progression shown in FIGURE 1. A more thorough discussion of this and other matters can be found in an audiology pocket guide format by Steiger and Miller (2017).
The U.S. Food and Drug Administration (FDA, 1977) promulgated federal regulations that serve as a guideline for determining the need for medical clearance for hearing aid use. We recommend consideration of the guidance provided in that document, though it will no longer be enforced at the federal level (FDA press release, 2016). States, however, may require that audiologists continue to adhere to this guideline. Clarifications and more comprehensive and rigorous recommendations were offered by the American Academy of Otolaryngology–Head and Neck Surgery (AAO-HNS, 1993, 1994, 2015). In our opinion, some of those recommendations would lead to a high over-referral rate. FDA guidelines for determining the need for medical clearance for hearing aid use, and AAO-HNS recommendations, are given below.
- Child younger than 18 years of age (FDA, 1977).
- Otalgia or discomfort in the ear (FDA, 1977).
- Visible congenital or traumatic deformity of the ear (FDA, 1977).
- Visible evidence of significant cerumen accumulation or a foreign body in the ear canal (FDA, 1977). Visualization of blood, pus, cerumen plug, foreign body, or other material in the ear canal (AAO-HNS, 2015). Note: Audiologists should determine if cerumen management is within the scope of practice in their state and manage or refer when warranted.
- History of active drainage from the ear within the previous 90 days (FDA, 1977) or within the previous six months (AAO-HNS, 1993, 1994).
- History of sudden or rapidly progressing hearing loss within the previous 90 days (FDA, 1977) or within the previous six months (AAO-HNS, 1993, 1994).
- Acute or chronic dizziness (FDA, 1977) or recurrent episodes of dizziness (AAO-HNS, 2015).
- Unilateral hearing loss of sudden or recent onset within the previous 90 days (FDA, 1977). The AAO-HNS (1993, 1994) clarification of unilateral hearing loss: air-conduction pure-tone PTA (500, 1000, 2000, and 3000 Hz) difference of 15 dB or greater. AAO-HNS (2015) concurred but did not identify test frequencies. They did, however, add unilateral or asymmetrically poor word recognition scores defined as a difference between the ears of greater than 15 percent.
- Audiometric air-bone gap of 15 dB or more at 500 Hz, 1000 Hz, and 2000 Hz (FDA, 1977). AAO-HNS (2015) criteria included unexplained conductive hearing loss or abnormal tympanogram but did not elaborate.
- Bilateral hearing loss greater than 90 dB (AAO-HNS, 1993, 1994; frequencies not specified). The AAO-HNS (2015) suggested greater than 30 dB (frequencies not specified) or word recognition score poorer than 80 percent; we believe this would lead to over-referral.
- Hearing loss with history of tuberculosis, syphilis, human immunodeficiency virus (HIV), Meniere’s disease, autoimmune disorder, otosclerosis, Von Recklinghausen’s neurofibromatosis, or Paget’s disease of the bone (AAO-HNS, 1993, 1994) or history of ear infections or noise exposure, familial hearing loss, ototoxic medication use, otosclerosis, or head trauma related to onset (AAO-HNS, 2015).
Patients at Risk for Vestibular Schwannomas
Audiologists may wish to consider more specific options for vestibular schwannomas. Vestibular schwannomas most often occur unilaterally and cause unilateral or asymmetric symptoms and findings (rarer cases of bilateral vestibular schwannomas are not considered here). Patients at risk for vestibular schwannomas should be evaluated by an otologist and considered for magnetic resonance imaging (MRI). Audiologists may consider the following test findings, symptoms, and patient history:
- Symptoms and history: The significance of positive test findings may be tempered by whether they are explained by known acoustic or physical trauma, disease, or otologic treatment. Welling, Glasscock, Woods, and Jackson (1990), for example, reported a relatively high probability of vestibular schwannoma for patients exhibiting unexplained asymmetry of audiometric thresholds, word recognition score (WRS), and tinnitus. In contrast, they reported a lower probability of vestibular schwannoma for patients with isolated vertigo and historically explained unilateral hearing loss and tinnitus. This article’s authors suggested suspicious case histories may include the following:
- Unexplained unilateral or asymmetric hearing loss.
- Persistent unexplained unilateral or asymmetric tinnitus or vertigo/dizziness.
- Aural fullness.
- Facial paralysis, paresis or weakness.
- Welling, Glasscock et al (1990), of course, discussed asymmetric hearing as a symptom and finding. Below are criteria to identify pure-tone air-conduction thresholds as described by subsequent authors. Options include but are not limited to the following:
- AAO-HNS (1993, 1994) criteria as described above; the average difference in air-conduction thresholds between ears of 15 dB or greater at 500 Hz, 1000 Hz, 2000 Hz, and 3000 Hz.
- Obholzer, Rea et al (2004) recommendations: 15 dB threshold difference between ears at two adjacent frequencies for patients with unilateral hearing loss and 20 dB threshold difference between ears at two adjacent frequencies for patients with bilateral hearing loss. This option offered higher sensitivity but lower specificity than the AAO-HNS criteria. We prefer these criteria because they are simple to use and offer sensitivity that should mitigate the possibility of missing significant pathology.
- Zapala et al’s formula: Zapala et al (2012) offered a formula, based on a retrospective chart review of patients with unilateral acoustic neuromas, to calculate the risk of vestibular schwannoma for various audiograms. Considered in the formula were age, gender, and noise exposure history. The precise calculation is beyond the scope of this article and it may at first appear daunting. It can, however, be incorporated into a spreadsheet for easier use.
- Subsequent authors also have addressed the use of asymmetric word-recognition scores to suggest concerning asymmetries. We have noted ubiquitous use of Thornton and Raffin’s (1978) statistical approach to the identification of significant WRS asymmetry when measured with NU-6 word lists, and also the 15 percent criteria recommended by the AAO-HNS (2015). The former sometimes allows asymmetry greater than 15 percent and thus will result in lower sensitivity and higher specificity.
- Other tests: The results of other tests may be considered at the discretion of audiologists, including but not limited to rollover, acoustic reflex thresholds, acoustic reflex decay, and auditory brainstem response (ABR).
From the above, audiologists may form test batteries. The sensitivity and specificity of test batteries can be manipulated by selection of strict or lax interpretation criteria (Turner, Frazer et al, 1984; Turner, 2013). A full discussion of this topic is beyond the scope of this article, but typically a strict test battery interpretation criterion will result in lower sensitivity and a higher miss rate, but fewer false alarms and a higher specificity. In contrast, a more lax criterion test battery interpretation criteria will result in higher sensitivity and a lower miss rate, but more false alarms and lower specificity. Intermediate criteria may be adopted. This is a complex clinical judgment that each audiologist must make on a case-by-case basis, based on his or her level of comfort with risk. Moreover, the degree by which a test result exceeds criteria should be considered. This article’s authors generally tend toward a relatively strict test battery interpretation, while monitoring borderline patients aggressively.
Sudden Sensorineural Hearing Loss
Sensorineural hearing loss with sudden onset warrants immediate referral. Based on the definition of sudden sensorineural hearing loss by the AAO-HNS (2012), we offer the following considerations:
- Pure-tone thresholds: A sudden decrease or asymmetry in hearing of at least 30 decibels (dB).
- Involved frequencies: At least three consecutive test frequencies.
- Duration: Onset over no more than 72 hours.
The guideline authors, however, recognized that clinicians might wish to err on the side of caution by adopting more liberal referral criteria and using clinical judgment. We concur. Moreover, the above authors reported that corticosteroid treatment appears to be most effective when prescribed within two weeks of onset, with diminishing benefit up to six weeks. This also should be considered when making referral decisions.
Interpretation of Wide-Width Tympanograms and Otoscopy
In general, an abnormal tympanometric pattern can be caused by more than one disorder. This is true of wide-width tympanograms, which can be caused by many disorders including but not limited to otitis media, cholesteatoma, glomus tumor, patent PE tubes, occluded PE tubes, and tympanic membrane perforation. We cannot cover all possibilities in this article, so we begin this section urging vigilance when wide-width tympanograms are measured. Symptomatic patients should be considered for referral for medical evaluation; symptoms include but are not limited to otoscopic evidence of otorrhea or blood, reported otalgia, significant conductive hearing loss. That said, the more common causes of wide-width tympanograms are discussed below.
- Wide-width tympanograms with normal ear-canal volumes might indicate otitis media. Otoscopically, otitis media with effusion may manifest as a cloudy tympanic membrane and/or air bubbles or an air-fluid line (American Academy of Pediatrics, AAP, 2013). Wide-width tympanograms with positive otoscopy should be considered for referral, especially when air-bone audiometric threshold gaps meet criteria given in the FDA hearing aid fitting guidelines or other guidelines above. When otoscopy and audiometrics are negative, it seems reasonable to audiologically monitor patients with wide-width tympanograms. We offer the American Speech-Language-Hearing Association (ASHA) recommendations for tympanometric screening (ASHA, 1997). At a minimum, the tympanogram should be repeated in six to eight weeks and referral is indicated if findings or symptoms persist or worsen. Acute otitis media may manifest as a budging erythematic tympanic membrane (AAP, 2013).
Pressure Equalization Tubes
- Wide-width (flat) tympanograms with large ear-canal volumes are findings consistent with patent pressure equalization tubes that can often be visualized during otoscopy. Asymptomatic patients with patent pressure equalization tubes should be encouraged to follow the managing physician’s advice on care and follow-up including dry-ear precautions.
- Symptomatic patients with patent pressure equalization tubes should be referred to the managing physician. Symptoms include otoscopic evidence of otorrhea or blood, reported otalgia, significant conductive hearing loss.
- Wide-width tympanograms with normal ear-canal volumes might indicate obstructed pressure equalization tubes, possibly with otitis media. Whether or not symptomatic, we recommend otoscopic confirmation of the obstruction and audiometrics followed by referral to the treating physician.
Tympanic Membrane Perforations
- Wide-width (flat) tympanograms with large ear-canal volumes might indicate a tympanic membrane perforation that can often be visualized during otoscopy.
- Asymptomatic and previously undiagnosed patients should be advised to follow dry-ear precautions and be referred to an otolaryngologist.
- Asymptomatic patients with previously diagnosed tympanic membrane perforations should follow the managing physician’s advice.
- Symptomatic patients with tympanic membrane perforations, whether or not previously diagnosed, should be referred to the managing physician. Symptoms include otoscopic evidence of otorrhea or blood, reported otalgia, significant conductive hearing loss.
Interpretation of Narrow-Width Tympanograms and Otoscopy
As stated earlier, an abnormal tympanometric pattern can be caused by more than one disorder. This is true of narrow-width tympanograms, which can be caused by many disorders including but not limited to monomeric or dimeric tympanic membranes, ossicular discontinuity, or otosclerosis. As a general rule, symptomatic patients should be referred for medical evaluation; symptoms include otoscopic evidence of otorrhea or blood, reported otalgia, significant conductive hearing loss. More specific considerations are given below.
Monomeric or Dimeric Tympanic Membranes
- Monomers and dimers result from disease or trauma causing the loss of at least the fibrous layer of the tympanic membrane. This causes tympanic membrane hyperflaccidity, which manifests on a tympanogram as high static compliance and narrow width. Typically, monomers and dimers cause no worse than a small high frequency conductive loss (Gopen, 2013). In addition to otoscopic confirmation, we recommend pure-tone audiometrics. Asymptomatic patients should be followed routinely.
- Ossicular discontinuity typically results from trauma. This causes tympanic membrane hyperflaccidity, which manifests on a tympanogram as high static compliance and narrow width. In contrast to monomers and dimers, ossicular continuity typically manifests audiometrically as a more significant conductive hearing loss across the entire audiogram. Whether or not symptomatic, we recommend otoscopic inspection and audiometrics followed by referral for medical evaluation consistent with the FDA pure tone air-bone gap criteria discussed earlier in this paper.
- Otosclerosis involves an alteration and reformation of bone that fixes the stapes in place. This limits the motion of the middle ear structures resulting in a narrow width but often normal static compliance and unremarkable otoscopy. We recommend audiometrics as otosclerosis often manifests as a conductive hearing loss with a bone conduction notch at 2000 Hz reflecting a change in middle ear resonance. We recommend counseling regarding potential audiologic and medical treatments and referral for medical evaluation consistent with the FDA pure tone air-bone gap criteria discussed earlier in this paper.
Many disorders, medications, chemicals, and trauma can cause or exacerbate tinnitus. These exacerbating factors and all of the above referral criteria should be considered when deciding on the need for referral. Audiologists’ goal should be to identify patients with neural tinnitus who are therefore candidates for audiologic treatment. Other tinnitus patients are candidates for medical evaluation (ASHA, 2014; Henry, Zaugg et al, 2010; Tunkel, et al, 2014; Simmons, et al, 2008). Tinnitus-specific triage referral criteria offered by Henry et al, included:
- Tinnitus of somatic origin including pulsatile tinnitus, especially pulsations consistent with heartbeat.
- Trauma, facial palsy, or sudden hearing loss.
- Mood disorder suicidal ideation or obvious mental health problems require referral to a mental health provider.
- Symptoms associated with movement of head or neck including tinnitus modulation.
ASHA includes the above and also recommends referral for the following:
- Symptoms associated with movement of head or neck: Presumably, this is in reference to modulation of tinnitus by head, neck, or eye movement, which though common deserves medical evaluation.
- Otalgia, otorrhea, malodor, dizziness, and vertigo.
Many disorders, medications, chemicals, and even trauma can cause or exacerbate dizziness, imbalance, and/or vertigo; these exacerbating factors and all of the above referral criteria should be considered; however, benign paroxysmal positional vertigo (BPPV) is the most common cause of peripheral vertigo (Froehling, Bowen, et al 2000), especially in patients 80 and older (Hain and Ramaswamy, 1999). Bhattacharyya, Baugh, et al (2008) recommended that clinicians differentiate BPPV from other causes of imbalance, dizziness, and vertigo for which the severity of serious medical sequelae may be greater. Patients with BPPV are candidates for audiologic treatment; other dizzy patients are candidates for medical evaluation (ASHA, 1990). Therefore, medical referral should be considered for:
- Patients with findings atypical to BPPV, including symptoms that are not provoked by head position including negative findings with the Dix-Hallpike.
- Patients with BPPV symptoms showing no improvement after two to three canalith repositioning treatments. Treatment failure can occur with misdiagnosis of the canal(s) affected by BPPV or misdiagnosis of another or even a concomitant disorder (Smouha and Roussos, 1995)
We offered here a synopsis of referral options and considerations for audiologists as a resource to augment, but not to replace, clinical judgment.
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